Wire clamp assembly



April 6, 1965 J. HAYDU ET AL WIRE CLAMP ASSEMBLY Filed Jan. 21, 1965 -INVENTORS JOHN L. H AYJDU 'UELAND E. LAWRENCE AT TORN EY United States Patent 3,177,456 WIRE CLAMP ASSEMBLY John L. Haydu, Milwaukee, and Leland E. Lawrence, Wauwatosa, Wis., assignors to Allen-Bradley Company, Milwaukee, Wis., a corporation of Wisconsin Filed Jan. 21, 1963, Ser. No. 252,724 7 Claims. (Cl. 339-95) This invention relates to Wire clamp assemblies for attachment to the terminals of electrical relays and similar devices, and it more particularly resides in an improved clamping member for such an assembly.

Wire clamp assemblies for devices such as electrical relays 0r switches in which a terminal member extends from the device usually include a termnial screw threadedly engaged with the terminal member and a clamping member movable with the terminal screw that serves to clamp a connecting wire to the terminal member in a mechanically and electrically secure connection.

A great many forms of clamping members have been devised, but none has heretofore proven entirely satisfactory. For example, many older clamping members allow lateral or axial movement or twisting of the wire and mechanical or electrical failure may result. Others provide a secure connection, but only if great care and effort are taken in making the connection. Some older clamping members are designed for connecting Wires of only a very limited size range. Many such connectors are completely unsatisfactory for cases when two wires of different sizes must be connected to the same terminal.

Even those clamping members which afford relatively secure connections are not wholly satisfactory in practical use, primarily because they provide an adequate connection only when a wire is inserted from one, or at the most two, directions. Thus, care must be taken in orienting the clamping member during assembly of the device in which it is incorporated and this can result in substantial increases in the time and expense of manufacture.

To overcome the foregoing and other disadvantages of previously devised clamping members, it is an object of this invention to provide a wire clamp assembly which allows for simple yet secure connections in all situations.

It is another object of this invention to provide a clamping member which is adapted to give a mechanically and electrically secure connection by deforming the connected w1re.

It is a further object of this invention to provide a clamping member which can accommodate wires of widely varying sizes.

It is still another object of the invention to provide a clamping member adapted to connect wires of different sizes securely to a single terminal.

It is a still further object of the invention to provide a clamping member adapted to connect wires introduced from one or more of several directions.

It is still another object of the invention to provide a clamping member which can be assembled with the usual form of relay or other device without excessive time for orientation being required.

It is a still further object of the invention to provide a member which will have a secure clamping action even when less than maximum care is used introducing the wire or wires being connected.

It is a still further object of this invention to provide a clamping member which may have a locking action which further improves the resultant connection.

It is still another object of the invention to provide a clamping member with all the foregoing advantages but which is still simple and inexpensive to manufacture.

Other objects and advantages will appear from the description to follow. In the description, reference is made to the accompanying drawing, forming a part here- Patented Apr. 6, 1965 of, in which there is shown, by way of illustration and not of limitation, a specific embodiment of the invention.

In the drawing:

FIG. 1 is a fragmentary front view in elevation, with parts shown in cross section, showing a wire clamp assembly formed according to the invention and connected to a terminal of an electrical relay, with the clamping member being shown in a view in cross section taken along the plane 11 shown in FIG. 2,

FIG. 2 is a view in perspective showing the upper surface of the clamping member of FIG. 1,

FIG. 3 is a view in perspective showing the undersurface of the clamping member of FIG. 1,

FIG. 4 is a front view in elevation of the clamping member of FIG. 1,

FIG. 5 is a view in cross section of the clamping member of FIG. 1 taken along the plane 5-5 shown in FIG. 2, and

FIG. 6 is a bottom plan view of the clamping member of FIG. 1.

Referring again to FIG. 1, the reference numeral 1 therein designates the case of a conventional electrical relay (not shown). A horizontally disposed, fiat surfaced terminal member 2, which extends into the relay, is mounted on the case 1 with its upper surface substantially co-planar with a horizontal ledge 3 formed in the case 1. A. vertical Wall 4 formed in the case 1 rises upwardly from the rear edge of the ledge 3 and, as is usual practice, upstanding barriers 5 are disposed on either side of the terminal 2 to shield it from adjacent terminals (not shown). The ledge 3, wall 4 and barriers 5 form what is essentially a box-like receptacle having an open end and an open top and on the floor of which the terminal 2 is disposed. Although this represents a typical case construction with which a clamp assembly formed according to this invention is particularly useful, the invention is not intended to be limited thereby since it may find use in many other applications. Also, the invention is useful with electrical devices other than relays. For these reasons and since the invention may be fully understood without reference to any particular device or case construction, the case 1 and the relay referred to herein have not been shown or described in detail.

The wire clamp assembly of the invention generally comprises a vertically disposed terminal screw 6 and a plate-like, horizontally disposed clamping member 7. The screw 6 has a slotted head 8 and its shaft includes a narrowed intermediate neck portion 9 and an end or bottom threaded portion 10. The threaded portion 19 is engaged with a threaded opening 11 in the terminal member 2, whereby the screw 6 may be moved vertically with respect to the terminal member 2.. That portion. of the terminal screw 6 that projects below the terminal memher 2 is received in an opening 12 formed in the case 1.

The clamping member 7 comprises a substantially square, plate-like base 13, the sides of which are somewhat shorter than the distance between the barriers 5 and which has an approximately central and circular aperture 14 therethrough. The clamping member '7 is mounted on the screw 6 with the aperture 14 encircling the neck portion 9. The aperture 14 is large enough to provide a relatively loose lit with the neck portion 9 so as to prevent binding, but is smaller than the outside diameter of the head 8 or the threaded portionltl. The member 7 is, therefore, held captive on the neck 9 and is movable upwardly or downwardly with the screw 6'. This captive mounting may be accomplished in any well-known manner such as by staking the member 7 to reduce the size of the aperture 14 after the member 7 has been slid'over the portion 19 or by providing an unthreaded screw shaft with a diameter smaller than the aperture 14 and rolling on the threads of the portion after the member in v 1 place.

The clamping member 7 may be formed of any suitable material. in the member 7 are intended to deform a connected Wire so that a relatively strong, hard materialsuch as steel should be chosen, a

The undersurface of the base 13, as seen in FIGS. 1, 4

As will be described, however,'ribs formed 'ferred to as front and rear ribs.

ing ribs 16 extend forwardly and rearwardly with their branches 18 extending toward opposite side edges of the aperture 14; For purposes of description, the ribs 16 on either side of the aperture 14 in FIGS. 1 and 4 arereferred to'herein as side ribs and. the remaining ribs 16 are re- Again, however, it

' shouldbe understood that when the member 7 is-viewed andl6 is provided with downwardly extending rib means '15 in the form of a square surrounding the'aperture 14 and inscribed Within the square 'of the base 13 with the corners of the inscribed square being approximately at 'from any side there-will be two-side ribs, a frontrib, and a rear rib.-

In FIG; 1, theclamping member 7 is shown as it ap pears whena relatively larger :Wire and a relatively the mid-points ofthe sides of the base'13 so that thesides. I I ofthe square 15 are parallel todiagonals drawn between a the corners of the'base 13. Thegsides of the square'15 slope upwardly, as seen in FIGS. 1 and 4, from its corners to approach theplane of the undersurface of the base 13" at about their mid-points. This arrangement provides what are essentially four independent, V -shape dribs 16,

each of which has an outer end or apex 17 laterally spaced from the aperture 14 and approximately at the mid-point Q of a side of the base 13 and each of whichhas divergent branches 18 which slope upwardlyand extend inwardly from its outer end. j

1 As can be seen most clearly in FIG. 6, thedivergent branches 18 of each rib 16 extend toward opposite sides of the aperture 14,'and, referring for illustrative purposes to the lowermost rib 16 .in FIG. 6, a line A-A' drawn from the centerA'of the circular aperture 14 toa point A at the apex 17 of therib 16 bisects the angle formed by the branches 18. Since the line A-A is drawn to the center A of the aperture 14, it is 'perpendicular toa tangent B-B drawn to the near side of the aperture 14 the near side being that, point ,on the circumference of the aperture14 closest to the apex 17 and through which the line A-A' passes. The ends of the branches 18, which constitute the inner end of the rib 16, terminate ona line C'-C' parallel to'and short of the tangent B-B'. This geometrical arrangement of the ribs 16 and aperture 14 i is particularly desirable as will be described, and is easily provided due to the square configurations of the base 13 and the rib means 15, but it should'be apparent that the same general geometrical arrangement could be provided for'less or more ribs 16. p 1 7 j Referring particularly now to FIGS. 2 and 6, it can be seen that the upper surface of the base 13 is provided with upwardly projecting means comprising a set offour upstanding, hemispherical projections 19, the horizontal center of each of which is located at approximately the mid-point of a sideof the square'ISsoas to be near to the ends of the branches 18 of twoadjacent ribs 16. The projections 19 are preferably formed by stamping the 7 base 13, and thus have corresponding depressions on'the underside of the base 13 which define ,theends of the. rib

branches 18. Considering any rib 16 individually, again 7 such as the lowermost rib 16 shown in FIG; 6, it can "be seen that the c'enters oftheprojections, 19 at the'ends of each of the rib branches 18 are on the side toward-the tangent 'B-B'," and away'from the apex '17, of the line C-C'. The projections 19jand the rib means 15'can easily'be formed in' the base 13 by alsingle. stamping operation, thusallolwing for simple and inexpensive manufacture.

The operation of the clamping member7' may' now S be described. Inthe particular embodiment of the .in-

.vention shown herein, the member 7 'has four' operating smaller wire 21, bothforrned of copper ,or other conventional electrically conductive materials and approximately of a circularcross section, are clamped to the terminalZ." As has been previously described, the member 7 is held captive on the neck'jportion 9 and is thus movable with the screw '6 toward and awayfrom the 'ly their proper positions against and on opposite sides of :the neck9.

1As the member 7 is then moved downwardly with the terminal screw 6, the side ribs 16 will contact the high points of the wires 20, 21 at points on the ribs 16 that are laterally" spaced from the aperture 14. If therwires 20,21 are not already lying against the neckportion 9,

CO V

a rib v16 cannotflbe clamped since. the rib 16 would make further downward movement of the-member 7 will result in a carnming action by the side-ribs 16in which a hori- 'zontal force. component urges the wires 20,21 toward the neck portion 9 and a vertical force componentvholds the wires'20, 21 against the terminal 2. At the completion ofa clamping action, the, wires 20, 21'jare .in :the positions of FIG. 1; that is, they are wedged at the juncture-0f the neck 9 and'tertninal 2 by theside ribs 16.

The mernber 7"is capable of clamping wires within a large .fixed. range of wire sizes. jFromFIG'. 1 it can be appreciated that there is a clearanceunder the inner portions of the ribslfi when their outerends are resting On the terminal 2 and wireslsmaller than this clearance cannotbefeifectively clamped. Similarly, wires that .are too large cannot be held by the nieinberll.v For example, a wire of circularycross section with a radius larger than the distance betweenjtheneck 9 and the outer end .of a

contact inside" the high point of the wire'and would thus tendto push the wire out rather than draw .itin. Although the length of the 'ribs16 and the. clearance under them are the'outer theoretical limits of a range of .wire sizes for the clamping membei 7, it should gbeiobviouslthat practicalrange of wiresizes for any design-will be somewhat more limited,- 7 I h In addition tortheir wedg'ing'eifect, the ribs 16 have a deforming action. Since the member 7 is of a material substantially harder than the wires 20, ZL-the ribs 16 willrupon-the application of a slight forcegcutinto the wires 20, 21 to form and later rest inflat, bottomed,

transverse grooves thereinwhichis very advantageous in preventing axiallor twisting movement of the wires positions since wires may be introduced thereunder from any of the four sides of the base13. When the member ,The clamping and. deforming action ofv the ribs 16 is "enhanced by theirfbeing .V+shaped;withythe divergent .7 is viewedfiom. any of its four sides, it appears as seen in elevation in. FIG. 4,1015-218 seen in cross section in FIGM L That is, two ribs 16 are located, onlaterally opposite sidesof the aperture 14 and extend inwardly and 1 upwardly. from opposite edges of'the' base 13 toward'the aperture 14,'with their branches "18 extending toward the front and rear edges of the aperture 14 The twojrernainbranches, 1,8. The grooves cut into, the wires 20, 21 by the. branches 18 are fdivergent. and further: insure against {pulling or t wisting; Also, thebranches 18-diverge equij angularly.frotnftheline A A leading-to the center of the aperture. 114, "and exert '7 inward forces whereby the w res 20, 21; are necessarily urged along the line A r- A and d ec lr aga n t h jneck 9: The :bmneheslfilfurr s ther deform the wires 26, 21 by partially kinking or bending them about the neck 9 to enhance the clamping action. Although the V-shaped ribs 16 are thus particularly advantageous, linear ribs, such as one extending along the line A-A, can be substituted without departure from the invention. The term rib as it appears in the claims appended hereto, therefore, is not intended to be limited to a V-shaped rib unless otherwise specified.

The branches 18 of the side ribs 16 are located inwardly of the front and rear edges of the base 13, whereby they operate effectively even when the wires 29, 21 are not inserted all the way under the member 7, as often happens due to carelessness or for other reasons.

From FIGS. 1 and 4, it can be seen that the branches 13 oft he front and rear ribs 16 extend to opposite sides of the aperture 14 to approach the ends of the branches 18 of the side ribs 16 and form what is essentially an inverted V-shaped groove under the base 13 on either side of the neck portion 9. The presence of this V-shaped groove has, however, no particular effect, since for wires 20, 21 of any reasonable size the point of contact with the side ribs 16 will be laterally outward of the apex of the V. The wedging action of the member 7 is, therefore, due substantially to the side ribs 16.

As previously set forth, the member 1'7 has four operating positions, and this contrasts sharply with usual clamping members which have only one or two operating positions. It should be obvious, however, that a clamping member with even more operating positions, such as one having six ribs 16 arranged in hexagonal form, could be provided within the scope of the invention.

The four ribs 16 in a symmetrical arrangement with the square base 13 give the clamping member 7 special advantages when used with the conventional case construction of FIG. 1. Since the sides of the base 13 are only slightly smaller than the distance between the barriers 5, when the member 7 is inserted between the barriers 5, two opposite edges of the base 13 serve as locating edges and insure that one side of the base 13 faces. outwardly so that the member 7 is automatically placed in an operating position. Again, the member 7 can be placed between the barriers 5 with any of the sides of the base 13 facing outwardly thus saving considerable effort in assembly over older rectangular or other clamping members which are arranged to be inserted between barriers in only one or two positions. A similar locating effect will arise if there is only one barrier 5 or if any suitable projection is formed in the case 1 and placed appropriately close to the terminal 2. Similarly a hexagonal base 13 With six ribs 16 could be provided with the distance between opposite sides of the hexagon being somewhat smaller than the distance between the barriers 5.

lthough the locating effect afforded by the square base 13 is advantageous, a base 13 without a locating edge or locating edges, such as a circular base, could be used and would still allow for a clamping member having the advantage of having more than the usual one or two operating positions.

Although the clamping member 7 is shown in FIG. 1 as clamping wires 20, 21 of the usual circular cross section, it should also be readily apparent that the member 7 will be useful with wires of other cross sectional configurations when this is desirable.

In FIG. 1, it can be seen that the underside of the head 8 of the screw 6 is in direct contact with the centers or high points of the projections 19 rather than with the upper surface of the base 13. This is particularly advantageous when, as is seen in FIG. 1, it is desired to connect two wires 21), 21 of different sizes to the same terminal 2. As can be seen in FIG. 1, the base 13 tends to tilt downwardly away from the larger wire 21 from left to right as seen in FIG. 1. If there were no projections 19 on the upper surface of the base 13, it can be seen that the screw 6 would contact the upper surface of the base 13 at a point on the edge of the head 8 to the left of the larger wire 20 as seen in FIG. 1. Since the member 7 should have a loose fit about the neck portion 9 to prevent undesirable binding, further movement of the screw 6 downwardly would result in the member 7 being pivoted about the fulcrum afforded by the wire 20 and in a counterclockwise direction as seen inFIG. 1 thus lifting its right-hand edge from the smaller wire 21 and providing a poor connection. As can be seen in FIG. 1, however, the projections 19 on the left side of the neck portion 9 are located inwardly of the point of contact with the left-hand rib 16 and the larger wire 21. Thus, further movement of the screw 6 downwardly tends to cause the member '7 to be pivoted in a clockwise direction about the wire 29 as seen in FIG. 1 to insure a secure connection with the smaller wire 21.

In the particular embodiment of the invention shown herein, the high points of the projections 19, which serve as points of contact with the screw 6, are located approximately on the tangent B-B and this is a special advantage of the square, symmetrical construction shown. Since the side ribs 16, even if they extend past the aperture 14, will contact a wire of any finite size along a line parallel to and outside of the tangent B-B, the projections 19 associated with the rib 16 contacting the larger of two wires will insure effective connection. Such connection is possible even with two wires of widely differing sizes.

In the present embodiment of the invention, the line C-C represents the innermost point at which a wire may be contacted since it defines the ends of the ribs 16. If the member 7 is to be designed to connect only large wires, whereby the point of contact with the wires will be a substantial lateral distance from the tangent B-B', it is possible to provide projections 19 that are laterally outside of the tangent B-B'. In essence, it is necessary only that there be projections 19 on the upper surface of the base 13 that are on the side away from the outer end of the rib 16 of the line of contact of the rib 16 with any wire within the size range for which the member 7 is designed.

In the particular embodiment of the invention shown herein, there are four upstanding projections 19 and this particular arrangement is advantageous in that it allows formation of the member 7 by a single stamping operation. From the standpoint of function, however, it should be obvious that other projecting means arrangements are possible. For example, an upstanding ring or collar encircling the aperture 14 could be provided which would also insure effective operation for any operating position of the member 7. If desired, the upstanding projections 19 may be provided with sharp edges or points so as to provide a locking action with the underside of the head 8 of the screw 6 thus further insuring a secure connection.

Since it should be apparent from the foregoing that a number of variations from the particular embodiment of the invention shown herein are possible within the scope of the invention, the invention is not intended to be limited except insofar as such limitations appear in the following claims.

We claim:

1. In a wire clamp assembly for a terminal member the combination comprising: a vertically disposed terminal screw; and a horizontally disposed plate-like clamping member that has an aperture which encircles the terminal screw, said clamping member being eng-ageable by the screw to be moved downwardly toward the terminal member, said clamping member having an undersurface adapted to face the terminal member and a downwardly extending rib on its undersurface that is V-shaped when viewed from said undersurface with its apex laterally spaced from the aperture and with its branches sloping upwardly from the apex toward the undersurface of the base, said branches extending divergently toward opposite sides of the aperture to be adapted to form inwardly opening acute angles with the terminal member.

2. In a clamping member for a terminal assembly the 7 combination comprising: a plate-like base with a substantially ci-rcular terminal screw receiving aperture there throughra rib .formed on one surface of the base that is V-shaped when viewed from said onev surface with its apex laterally spaced from the aperture and located ona line 1 perpendicular to. a tangent drawn to thenear side of the aperturerand with its branches sloping toward said one surface and extending inwardly along divergent lines ex- I 'br-anches'sloping toward the base and extending divergently toward opposite sides of the aperture. '7; In a clamping. member for a terminal assembly the combination comprising: a substanitally square plate-like base having a substantially central and circular aperture therethroughgoutwardlyextending ribmeans formed, on

I one surface of thebase, said rib means being in the form tending toward opposite sides of the aperture to terminate i at inner ends which lie on a lineparallel to and short of the. tangent; and a pair of upstanding projections on the other tsurfacenofthe base each of which is horizontally near the. inner end of one branch, said projections being adapted to serve as points of engagement with a terminal screw head, with said points being horizontally disposed along a line parallel to and on the side toward the tangent of'the line of termination of the-branches.

3. The combination of claim 2 wherein the line per pendicular tothe tangent and extending to the apex bisects the angleiormed by the rib branches. 7 7

4. The combination .of claim 2 wherein there are two ribs anditwo. associated pairs of projections disposed Jon opposite sides of the aperture '5.':The combination of claim 2 wherein the base is' sub- 'stantially square with the aperture at approximately its center and there are four ribs and associated pairs of pr.o-. jections with the apex of one ribbe'ing located at approxi mately the mid-point of each of the sides :of the base.:

of an inscribed square the corners of .which are at approximately the mid-points of the sides of the base and which surrounds the aperture, the sides of the square formed by the rib means slopingdownwardly from the corners thereof to approach'the plane of saidone surface 6. A clamping member for a terminal assembly com prising: a plate-like polygonal base with a plurality of pairs of substantially parallel'opposite' sides'and a terminal screw receiving aperture extending therethrough at approximately its geometric center; and a pluralityof V shaped ribs formed on one surface of the base, there being ,for each side of the base a rib which has itsapex at approximately -the mid-point of saidsidea-nd which has its 7 formed by the rib means.

at approximately their mid-points; and four upstanding projectionson the othersurfacey-of the base thatare adapted to engage the head'of' a terminal screw and are horizontally located so that one projection is approximately overthe midpoint of each side of the;square References Cited bylthe Examiner UNITED. STATES PATENTS JOSEPH D. SEERS, Primary Examine r THOMAS J. HICKEY, Examiner. 

6. A CLAMPING MEMBER FOR A TERMINAL ASSEMBLY COMPRISING: A PLATE-LIKE POLYGONAL BASE WITH A PLURALITY OF PAIRS OF SUBSTANTIALLY PARALLEL OPPOSITE SIDES AND A TERMINAL SCREW RECEIVING APERTURE EXTENDING THERETHROUGH AT APPROXIMATELY ITS GEOMETRIC CENTER; AND A PLURALITY OF VSHAPED RIBS FORMED ON ONE SURFACE OF THE BASE, THERE BEING FOR EACH SIDE OF THE BASE A RIB WHICH HAS ITS APEX AT APPROXIMATELY THE MID-POINT OF SAID SIDE AND WHICH HAS ITS BRANCHES SLOPING TOWARD THE BASE AND EXTENDING DIVERGENTLY TOWARD OPPOSITE SIDES OF THE APERTURE. 